Chromosome 3 is 7% of the human genome and encompasses 210 megabases of DNA. Despite its size, chromosome 3 has been slow to accumulate markers. Recently a large number of new markers have been generated for chromosome 3, as evidenced by the number of DNA segments assigned to chromosome 3: at HGM9 there were only 29 single copy DNA segments and at HGM10 there were 114 firmly assigned markers. Consequently, now we will be able to begin to construct maps for chromosome 3. The purpose of this workshop is to consolidate data from. many labs to construct physical, linkage and radiation maps for chromosome 3. These maps will establish the common bases for the maps, identify overlap, and identify areas that need resolution. The workshop will be held for two days in Denver, CO and will be hosted by the Eleanor Roosevelt Institute. The structure of the meeting will consist of brief presentations by each laboratory, and a working session to accomplish the following goals: 1) establishment of an initial set of ordered reference markers from either physical or genetic linkage studies; 2) to establish a set of canonical somatic cell hybrids which can be shared by investigators for regional mapping studies; 3) to identify a set of markers for which corresponding YACs will be isolated and shared, and 4) to develop agreements under which the various resources can be freely shared. The results of this meeting will be submitted for publication.